Automotive electrical components units have been increasing steadily with recent developments in electronic communications technology, and to control an increase in the number of wires, multiplex communications are beginning to be carried out by organizing a network in an automobile. With such trend, electrical components units connected to a vehicle-mounted network have been modularized.
As electrical components units of an automobile, an engine module 1, a rear seat module 3, door modules 5a to 5d, a driver's seat (D-seat) module 7, an instrument panel module 9, a passenger seat (P-seat) module 11, and a roof module 13 and the like are mounted, as shown in FIG. 4 by way of example. These electrical components units 1, 3, 5a to 5d, 7, 9, 11 and 13 are connected through various kinds of communication paths such as optical cables, i.e., a trunk line 15, a control-system communication line 17, and a car-body-system communication line 19 and the like, to organize a vehicle-mounted network.
When a vehicle-mounted network is organized by modularizing electrical components units in an automobile in this manner, an electrical components unit 43 connects a connector 45 on the electrical components unit 43 side optically and electrically to a connector 53 which is connected to optical cables 47a and 47b, a feeder line 49, and a ground line 51, as shown in FIG. 5 by way of example, and performs input and output of the optical cables 47a and 47b using a prescribed optical component 55. A signal inputted and outputted by the optical component 55 is processed by a CPU 57 to thereby drive various loads 59. A reference numeral 61 in FIG. 5 represents a power supply circuit.
Communications among the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 through such vehicle-mounted network are managed by the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 themselves, or a centralized management unit (not shown) provided separately from the electrical components units. This allows the organization of a very efficient communication system as long as a protocol and the like are fixed in multiple communications.
With customers' diverse needs for automobiles, the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 connected to the vehicle-mounted network need to be modified or updated individually, for automobiles as products to conform to each user's needs.
Also, to improve communication speed and the quality of communications in rapidly advancing communications technology, it is desirable that a communication system itself of a communication protocol applied to the vehicle-mounted network, such as a physical layer or a data link layer of the communication protocol, be modified or updated.
When the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 connected to the vehicle-mounted network, and the communication system and the like are modified or updated as described above, with the vehicle-mounted network communications being managed by the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 themselves or the separately provided centralized management unit, it is necessary that programs applied to these units be modified or updated as well with each modification or update to the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 mounted on an automobile and the communication system (a physical layer or a data link layer of the communication protocol) in the vehicle-mounted network.
However, as there are numerous combinations of the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 of an automobile depending on the user's taste for a car model, a car rank, and options on the car, an increase in the types of the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 mounted on an automobile involves an increase in management items for the units. Further, because the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 are modified or updated individually, modifications or updates to management programs and the like for the units increase in complexity.
In addition, if the management of the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43, as well as the management of the communication system that is modified or updated separately from the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 are done by the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 themselves or the separately provided centralized management unit, it is necessary to frequently modify or update both the management programs for the numerous electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43, and the management program for the communication system, which is inefficient.
The management of the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 and the management of the communication system by the electrical components units 1, 3, 5a to 5d, 7, 9, 11, 13 and 43 themselves or the separately provided centralized management unit will further cause the expansion of loads on CPUs in those units, setting limitations on the units' processing abilities.